星载被动微波资料(SSM/I)在2008年南方冰雪灾害监测中的应用试验

Probe into the Application of Monitoring Wet Snow in South China in Heavy Snowstorm and Frost Disasters 2008 with Satellite Passive Microwave Data (SSM/I)

2008年1月中旬至2月初,我国南方出现了罕见的大范围低温雨雪冰冻天气灾害。南方地区地面积雪的覆盖范围等灾害信息对于气象公共服务、决策服务都有着十分重要的意义。目前国内外开展的被动微波积雪研究,多关注高纬度、极地地区或高原地区的干雪状况,薄雪、湿雪的判识问题较少有人触及。而我国冰冻灾害期间,南方地区由于处于较低纬度带,昼夜温度在0℃上下起伏,雨、雪、雨夹雪天气的轮替,地面积雪恰恰多为湿雪、薄雪。积雪雪层由于液态水的存在将大大改变观测辐射信号,雪内少量液态水就能导致微波亮温值急剧上升。利用南方地区积雪冻融变化时微波亮温昼夜之间的差异变化,使用被动微波数据(DMSP-SSM/I)建立了对低纬度南方地区积雪监测的一种补充方法,结合其他积雪产品,可以获得更加完整的低纬度地区积雪分布信息。

During the January to the early February in 2008, the southern parts of China had suffered from a wide range of heavy snowstorms and frost disasters, which were featured by wide area, intense, long duration and disaster consequences. The disaster information of the covered area of the ground snow is very important for public meteorological service, and decision-making. Currently, the studies of passive microwave monitoring snow carried by European and American countries as well as China, are concentrated on the dry snow conditions in the area at higher latitudes, or in the polar regions.While there are few research focus on the thin snow, wet snow identification. Because the south part is located in the lower latitude, with the day and night temperature which fluctuates around 0℃ during the snowstorm and frost disasters, the mixture of rain, snow, and sleet make the snow fall on the ground always wet. The existence of the liquid water in the snow layer could greatly change the radiation signal, and a little liquid water in the snow could cause a sharp rising of the microwave bright temperature. Based on the bright temperature difference between the day and night when the changes of the snow in freeze-thaw in the South China, more snow distribution information in the lower latitude could be available by using the passive microwave data （DMSP-SSM/I） to build a compensate way of monitoring the snow in the South China combined with other snow products.